- The First Way: Motion.
- The Second Way: Efficient Cause.
- The Third Way: Possibility and Necessity.
- The Fourth Way: Gradation.
- The Fifth Way: Design.
Written by Rev. Fr. Kelvin Ugwu
Explanation…
The First Way: Motion
- All bodies are either potentially in motion or actually in motion.
- “But nothing can be reduced from potentiality to actuality, except by something in a state of actuality”.
- Nothing can be at once in both actuality and potentiality in the same respect.
- Therefore nothing can be at once in both actuality and potentiality with respect to motion
- Therefore nothing can move itself; it must be put into motion by something else.
- If there were no “first mover, moved by no other” there would be no motion.
- But there is motion.
- Therefore there is a first mover, God.
The Second Way: Efficient Cause
- Nothing is the efficient cause of itself.
- If A is the efficient cause of B, then if A is absent, so is B.
- Efficient causes are ordered from the first cause, through intermediate cause(s), to ultimate effect.
- By (2) and (3), if there is no first cause, there cannot be any ultimate effect.
- But there are effects.
- Therefore there must be a first cause for all of them: God.
The Third Way: Possibility and Necessity
- “We find in nature things that are possible to be and not to be:” contingent beings.
- Everything is either necessary or contingent.
- Assume that everything is contingent.
- “It is impossible for [contingent beings] always to exist, for that which can not-be at some time is not.”
- Therefore, by (3) and (4), at one time there was nothing.
- “That which does not exist begins to exist only through something already existing.”
- Therefore, by (5) and (6), there is nothing now.
- But there is something now!
- Therefore (3) is false.
- Therefore, by (2), there is a necessary being: God.
The Fourth Way: Gradation
- There is a gradation to be found in things: some are better (hotter, colder, etc.) than others.
- Things are X in proportion to how closely they resemble that which is most X.
- Therefore, if there is nothing which is most X, there can be nothing which is good.
- It follows that if anything is good, there must be something that is most good.
- “Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God”.
The Fifth Way: Design
- We observe that natural bodies act toward ends.
- Anything that acts toward an end either acts out of knowledge, or under the direction of something with knowledge, “as the arrow is directed by the archer.”
- But many natural beings lack knowledge.
- “Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God”.